Shank for mineral door-knobs



iin Pa Fica.

JOSHUA LAIRD, OF CINCINNATI.

OHIO.

SHANK FOR MINERAL DOOR-KNOBS.

Specification forming part of Letters Patent No. 6,473, dated May 22,r1849; Reissued November 22, 1853, No. 251.

To all whom t may concern Be it known that I, JOSHUA LAIRD, ofCincinnati, Hamilton county, Ohio, have invented new and usefulImprovements in the Mode of Manufacturing Door-Knobs .of lWIineral orother Analogous Material with Tubular Shanks; and I do hereby declarethe following to be a full, clear, and exact description of the same,reference being had to the annexed drawings, making part of thisspecification, in which- Figure l is a View of the knob when finished.Fig. 2 is a view without the mounting. Fig. 8 is a central section andt, 5, 6, 7, S, 9, l0 and 1l represent various analogous shanks.

The nature of my invention consists 1n manufacturing mineral door knobsor other analogous articles by inserting tubular shanks therein, thesmall amount of metal in which, in comparison to the bulk of mineraladmissible in the construction of such articles, in addition to thecharacteristics 1ncident to such shanks-viz, thinness, hollowness,elasticity and center vent' (whether through slots in, or, if the endinserted 1n the glass is closed, by the partial ylelding of the sides ofthe tube, or directly up the open tube) adopt them to this purpose, sothat the knobs made are complete fellows, are without any undue stra-inbetween the mineral and metal when annealed and are consequently brokenwith difficulty, either by contraction during the process, ortemperature or blows when in use; the contact of the mineral and metalspreading over a very large surface in proportion to the amount ofmaterials used and the difference of eXpansion between mineral andmetallic matter when brought into juxtaposition in this way beingdwindled in its dangerous tendency to a mere nothing.

Hitherto knobs have been molded around a pattern screw, which waswithdrawn before the mineral cooled too much or contracted too tightlyupon it. This plan is obviously too nice and uncertain ever to be madecheap. The glass may contract after the withdrawal of the pattern screwmore than will permit the entry of the spindle, or else the latter beingforced in, the glass must break, or reversing this order of things aloose fit is the result and various other objections are obvious. Knobshave also been cast around solid Shanks with variously devised heads togive hold and strength to the junction, but these are also liable tofatal objections and cause great loss to the manufacturer as well as tothe purchaser on account of their liability to fracture from too greatstrain of the glass upon the solid shank, from changes in thetemperature of the weather or from slight blows incident to daily use.There is also great liability to unevenness in surface from swellingsabout the shank head or imperfections in the casting of the same. Knobsof similar material to mine have also been essayed by casting the solidshank into the glass, &o., but this is less successful than any. All thediiiiculties which have been hitherto most prominent, I avoid by using ametallic tube whether made of cast, wrought or rolled metal. Thelongitudinal slit incident to making them of sheet metal allows playthat enables the metal to adapt itself reasonably and sufliciently tothe set of the contracting glass and is unquestionably the best mode ofmanufacturing mineral knobs. A slight upset o-n its end forms a strongand tenacious head around which the glass cools with an uniformity thatleaves the knobs precisely the same in size and figure and consequentlycomplete fellows. The center vent also plays an important part as by itthe glass is allowed room to rise up when displaced by the insertion ofthe shank upon the inside of the same and thus doubles the hold theglass could otherwise have on the shank if the shank were solid. Stillif the end of my tube is closed and large slots made in the sides of theshank I accomplish my purpose in an analogous manner. My knobs beingcomplete fellows a desideratum long sought after and of great value tothe sellers and buyers in the market) are capable of receiving the bestfinish, the mountings made for one being equally suited to iit any otheralthough the mountings are turned in a lathe. They drop right into placeand can be fastened on with cement or alloy, the hollow shank permittingthe instant cooling of the same by being filled with water.

It should be recollected that from 10 to 15 per cent of the solidshanked knobs fracture in cooling and that those even which do nofracture at that stage are to a very large percentage left with themineral so strained that a slight blow is suiiicient to set in motionthe tendency of the mineral to splinter,

owing to violence done to the process of crystallization by theunyielding shank. With my knob these diliculties are avoided and to suchan extent that it can be used as a hammer and still survive a reasonabletrial in that way.

The quantity of metal saved by my plan is also an object and pays theexpense of molding. I also prefer using rolled or sheet metal as it ismore free from burs or irregularities than cast metal, the former beingless exposed to disturbing influences or accidents in its manufacturefor this purpose and likewise furnishing a shank of at least equalstrength and greater lightness. The slight amount of metal cast, wroughtor rolled which I insert disturbs so little the hot mineral that asensible workman can hardly err in the quantity of Vmineral he shouldput into the mold. In the case however of the solid cast or wroughtshank, differences in the bulk of the shank, one to the other, tend tomar uniformity and precision in shape and size, so that the knobs do notalways match the mountings prepared for them and are therefore lesssusceptible of a cheap and complete finish. In a word the old processdoes not insure their being fellows. y

By my invention whether the shank is an open cylinder, prism, pyramid orcone without their apex or whether these forms or other analogous formsare closed at the end with slots in their sides where they are incontact with the glass or have a longitudinal slit or are without it,the knobs produced are always fellows and one knob will fit a latheturned mounting as well as any other knob in the lot. The shank whenconvoluted or crimped for instance will exhibit the same result. Allthis follows from the form and the small quantity of material used tomake the shank, in proportion to the limited bulk of glass admissible inmolding mineral knobs. A tube closed at the end inserted into the glasswill make a knob somewhat analogous but very far inferior to myl otherknobs. The metal will meet less resistance on the inside of the tubethan from the material surrounding the outside and forced against it bythe mold, and therefore a better knob will be made than those at presentin the market, but still it will only be` an inferior variety of mine.

Figure l, in the annexed drawing fully a nicety and thatproper for oneis equally suitable for any other. This accuracy, un1- Jormity,precision and neatness in the knobs, together with a capacity for beingreadily matched in case one of a pair should be broken, is attained witha saving in time, material, loss by breakage and other items soimportant to the wholesale manufacturer that his expenses are nearlycovered by the economy attained in the primary cost.

An examination of Figs. 4, 5, 6, 7, S, 9, 10, and ll, will exhibit manyforms for shanks of mineral door knobs involving the same principles andbased upon similar construction. F ig. 1l departing further from some ofthe points yet involving in a greater or lesser degree nearly all thecharacteristics I introduce into shanks for mineral door knobs.

Having thus fully described the nature, construction andv operation ofmy invention, what I claim as new and desire to secure by Letters Patentis- Making mineral knobs or other analogous articles such as curtainpins, drawer handles, &c. by inserting a tubular metallic shank with orWithout slots or a longitudinal slit,) into the vitreous or earthenmatter at a proper stage of the process, so that the quantity of metalin proportion to the bulk of mineral admissible in the case, andcomparatively to the extent of surface in contact with the mineral, isvery small, and the mineral consequently allowed to take its set about,lwithin or around the more or less elastic shank without any unduestrain upon or disturbance with its crystallization; thus rendering thedestructive tendencies arising from the unequal expansibility of themetal and mineral too slight practically to endanger the soundness anddurability of the finished knob or other analogous articles such ascurtain pins, drawer handles, &c.

JOSHUA LAIRD.

Witnesses EDWARD H. KNIGHT, THos. G. CLINTON.

f [FIRST PmN'rED 1913.]

